The kinetics and mechanism of sol-gel transformation on capillary ionotropic membranes of a copper alginate complex have been examined, complexometrically. Using a large excess of Cu2− ions over that of the alginate sol concentration, the pseudo-first-order plots were found to be relatively fast and curved significantly at short times, but became slow and linear at longer times. The rate law of gel formation was described by the form, (C∞ − C1) = B0exp(− Rft) + P0exp(− Rst), where these two gelation pathways showed a simple first-order dependence on both the metal ion and alginate sol. The kinetic parameters have been evaluated and a mechanism consistent with the kinetic data is suggested.